Heavy metals in two host-parasite systems: tapeworm vs. fish

Abstract

The tissue of two tapeworm species (Ligula intestinalis and Bathybothrium rectangulum) and body muscles of their fish host species were analyzed for heavy metal concentrations by standard methods using atomic absorption spectrometry. Regarding the values of accumulation ratio, the L. intestinalis accumulated 12.5–18.9 × more lead, 2.3–3 × more cadmium, and 4.4–14.1 × more chrome, compared to respective metal concentrations in muscles of cyprinid intermediate fish hosts. The gravid strobila biomass of the B. rectangulum accumulated 2.2 × more lead, 1.2 × more nickel, and 2.3 × more chrome compared with the respective concentrations in the muscles of the barbel Barbus barbus. Metal concentrations in the muscles of uninfected fish and by tapeworm infected barbels showed that the uninfected individuals exhibited 1.4 × more lead, 1.6 × more nickel and 1.7 × more chrome than the infected ones. Our study suggests that parasites are a useful bioindicator when evaluating environmental pollution of aquatic ecosystems by heavy metals.